How to Model 40cm tline Using LMG Tool

Started by saurabhsant on 9 Jan 2011 1:25 AM. Topic has 5 replies and 5667 views.
Last post on 10 Jan 2011 9:44 AM by Tawna.

Hi

I want to model a 40cm FR4 line in Cadence using the
parameters provided by manufacturer. I modelled a 4cm line using mtline
model and LMG tool in it. A parameter of fmax is set to 18GHz as I have
to operate at 16GHz.

When I tried to model a 20cm TLine, I received error message that, the tool cannot model lines with more than 5 wavelengths long.

Could somebody tell me how to model a 40cm transmission line in Cadence using given parameters? Which tool does this sort of modelling?

5 Replies

I want to model a 40cm FR4 line in Cadence using the parameters provided by manufacturer. I modelled a 4cm line using mtline model and LMG tool in it. A parameter of fmax is set to 18GHz as I have to operate at 16GHz.

When I tried to model a 20cm TLine, I received error message that, the tool cannot model lines with more than 5 wavelengths long.

Could somebody tell me how to model a 40cm transmission line in Cadence using given parameters? If yes, which tool does this sort of modelling?

I want to model a 40cm FR4 line in Cadence using the
parameters provided by manufacturer. I modelled a 4cm line using mtline
model and LMG tool in it. A parameter of fmax is set to 18GHz as I have
to operate at 16GHz.

When I tried to model a 20cm TLine, I received error message that, the tool cannot model lines with more than 5 wavelengths long.

Could somebody tell me how to model a 40cm transmission line in Cadence using given parameters? Which tool does this sort of modelling?

My guess is that you're using the standalone "lmg" tool (from the question). If so, this is obsolete and should not be used.

Instead, place an instance of the "mtline" component from analogLib, and choose the Type of Input as being "Field Solver". Then enter the physical parameters about the line in the property fields for mtline - you can still press "Display Cross Section" to visualize it.

The benefit of this approach is that the solver is run within the simulator, and generates the RLGC matrices (which are per-unit-length, and so do not have a length limitation). Because it's done in the simulator, you can parameterize the line's physical parameters, and sweep them, and so on.

With lmg, you could choose to produce either a lumped model or RLGC parameters. The lumped model had to know the physical length of the line, because otherwise it couldn't lump it - and this had limitations on the length of the line.

Since lmg has not been maintained, it will not have any of the improvements or fixes in the built-in field solver which is part of mtline. So you really should use that.

Do not use LMG . It is no longer supported and hasn't been updated (fixes, enhancements) in a number of years. If mtline isn't working, you may need to look at the nport. Please see the following Cadence On Line support solutions: